The Assessment Core has three major goals. The first is to ascertain approximately 150 new participants for the studies being conducted by all of the Subprojects within this next phase of our Program Project. The ascertainment process will include coordinating human participant reviews at the New York State Institute or Basic Research in Developmental Disabilities (IBR), as well as obtaining informed consent for new participants. We will also obtain new informed consents for the approximately 150 participants from our previous studies that will be continuing enrollment in our program, and an additional group of 20 - 30 younger adults with Down syndrome who will be studied in Subproject 3. The second major goal of the Core is to coordinate and conduct comprehensive assessments of our 300 study participants in close collaboration with investigators within Subprojects 1, 2, 3 and 4. Our third goal, in close collaboration with Subproject 1, 2, 3, 4 and the Genetics Core, will be to collect blood samples from program participants for analyses of biomarkers, genotype and epigenetic studies of methylation. The fourth goal will be to enter data from assessments into our Core database to facilitate analyses by Program Subprojects, and to maintain a separate participant tracking database. These activities will ensure that all Program participants are characterized using standardized procedures and common measures, providing rich descriptions of phenotype, facilitating analyses within individual Subprojects, and supporting interactions among Subprojects.